Wow what an awesome idea! How much did that cost you to have made? Are you worried at all about sharp edges hurting the rats? I've got all my rats in cages right now but I'm planning to make up a modified version of that rat rack to use soon and I've got a couple chewers lol. Great idea and I will definitely have to look into doing something like that for mine.

You should definitely watch out for rust and oxidation though rat urine is absolutely notorious for rusting non-coated metals.